This invention relates to the casting of light metals, such as aluminum and alloys thereof.
Light metals, such as aluminum and alloys thereof, are usually cast in the form of ingots which are then further worked, for example by rolling or extrusion. Such ingots are typically produced by the vertical, direct chill (DC) method.
It has been standard practice for many years to mount the metal melting furnace slightly above ground level with the casting mould at, or near to, ground level. The cast ingot is then lowered into a pit as the casting operation proceeds. Cooling water, after being applied as direct chill, flows into the pit and is continuously removed therefrom while leaving a permanent pool of some water within the pit.
During the direct chill casting of aluminum and its alloys, violent explosions may occur if the molten metal and the water used as a coolant in the process come into mutual contact under certain conditions. Recently it has been found that the explosive violence is greatly increased if the alloying element is lithium.
The mutual contact between the molten metal and water is usually the result of "run outs" which occur in which molten metal escapes in a break out from the sides of the ingot emerging from the mould. Much experimental work has been carried out over the years to establish the safest possible conditions for direct chill casting of aluminum. A well known paper on the subject is that of George Long in "Metal Progress" May 1957 pages 107-112. One of the solutions proposed in that report was to maintain a substantial depth of water within the pit.
It is the object of the present invention to provide a system which will rapidly quench molten metal break outs while direct chill casting, without contact between the molten metal from the break-out and wet surfaces.